Near-eye optical system

Abstract

A near-eye optical system receiving an image beam including a first optical waveguide is provided. The first optical waveguide expands the image beam in a first direction and includes first and second surfaces, first and second beam-splitting surfaces, and a plurality of first and second reflective inclined surfaces. The first and second beam-splitting surfaces are located in the first optical waveguide and disposed in a tilted manner relative to the first and second surfaces. The first and second beam-splitting surfaces have opposite tilt directions. The first and second beam-splitting surfaces receive an image beam incident from the first surface so that a first portion of the image beam passes through and a second portion of the image beam is reflected. The near-eye optical system further reduces a thickness of the optical waveguide and alleviates the issue that the image beam is not completely projected to the optical waveguide.

What is claimed is: 
     
       1. A near-eye optical system configured to receive an image beam, wherein the near-eye optical system comprises:
 a first optical waveguide configured to expand the image beam in a first direction and comprising:
 a first surface; 
 a second surface opposite to the first surface; 
 a first beam-splitting surface located in the first optical waveguide and disposed in a tilted manner relative to the first surface and the second surface; 
 a second beam-splitting surface located in the first optical waveguide and disposed in a tilted manner relative to the first surface and the second surface, wherein a tilt direction of the second beam-splitting surface is opposite to a tilt direction of the first beam-splitting surface, and the first beam-splitting surface and the second beam-splitting surface are configured to receive the image beam incident from the first surface so that a first portion of the image beam passes through and a second portion of the image beam is reflected; 
 a plurality of first microstructures and a plurality of second microstructures formed on the first surface, wherein the plurality of first microstructures comprise a plurality of first reflective inclined surfaces disposed on the first surface and arranged along the first direction, wherein a tilt direction of the plurality of first reflective inclined surfaces is the same as the tilt direction of the first beam-splitting surface; 
 wherein the plurality of second microstructures comprise a plurality of second reflective inclined surfaces disposed on the first surface and arranged along the first direction, wherein a tilt direction of the plurality of second reflective inclined surfaces is the same as the tilt direction of the second beam-splitting surface, the first beam-splitting surface is located between the second beam-splitting surface and the plurality of first reflective inclined surfaces, and the second beam-splitting surface is located between the first beam-splitting surface and the plurality of second reflective inclined surfaces, wherein a planar area is provided between the plurality of first microstructures. 
 
 
     
     
       2. The near-eye optical system of  claim 1 , wherein transmittances of the first beam-splitting surface and the second beam-splitting surface to the image beam are less than reflectances thereof. 
     
     
       3. The near-eye optical system of  claim 1 , wherein transmittances of the first beam-splitting surface and the second beam-splitting surface to the image beam are less than or equal to a ratio of a viewing angle range formed by the first portion of the image beam at a projection target and a viewing angle range formed by the entire image beam at the projection target. 
     
     
       4. The near-eye optical system of  claim 1 , wherein the plurality of first microstructures and the plurality of second microstructures are a plurality of convex microstructures, and the plurality of first reflective inclined surfaces and the plurality of second reflective inclined surfaces are surfaces of the plurality of convex microstructures. 
     
     
       5. The near-eye optical system of  claim 1 , wherein the plurality of first microstructures and the plurality of second microstructures are a plurality of micro recesses, and the plurality of first reflective inclined surfaces and the plurality of second reflective inclined surfaces are surfaces of the plurality of micro recesses. 
     
     
       6. The near-eye optical system of  claim 5 , further comprising a compensation waveguide disposed on the first surface, wherein the compensation waveguide has a plurality of convex microstructures complementary in shape to the plurality of micro recesses at a surface facing the first optical waveguide. 
     
     
       7. The near-eye optical system of  claim 6 , wherein a reflective layer or a partially-transmissive and partially-reflective layer is coated on the plurality of first reflective inclined surfaces and the plurality of second reflective inclined surfaces. 
     
     
       8. The near-eye optical system of  claim 1 , wherein a reflective layer or a partially-transmissive and partially-reflective layer is coated on all of the first surface, the plurality of first reflective inclined surfaces, and the plurality of second reflective inclined surfaces. 
     
     
       9. The near-eye optical system of  claim 1 , wherein a reflective layer or a partially-transmissive and partially-reflective layer is coated on both the plurality of first reflective inclined surfaces and the plurality of second reflective inclined surfaces. 
     
     
       10. The near-eye optical system of  claim 1 , further comprising a second optical waveguide configured to expand the image beam in a second direction, and the second optical waveguide comprises:
 a third surface, wherein the second surface is located between the first surface and the third surface; 
 a fourth surface opposite to the third surface; 
 a third reflective inclined surface inclined relative to the third surface and the fourth surface; and 
 a plurality of fourth reflective inclined surfaces disposed on the fourth surface and arranged along the second direction, wherein the image beam emitted from the second surface is reflected by the third reflective inclined surface and then is reflected by the third surface and the fourth surface to be transmitted in the second optical waveguide, and the plurality of fourth reflective inclined surfaces reflect the image beam toward the third surface so that the image beam is emitted from the third surface and transmitted to a projection target. 
 
     
     
       11. The near-eye optical system of  claim 10 , wherein an extending direction of each of the fourth reflective inclined surfaces is perpendicular to an extending direction of each of the first reflective inclined surfaces and perpendicular to an extending direction of each of the second reflective inclined surfaces. 
     
     
       12. The near-eye optical system of  claim 11 , wherein each of the first reflective inclined surfaces is extended along the second direction, each of the second reflective inclined surfaces is extended along the second direction, and each of the fourth reflective inclined surfaces is extended along the first direction. 
     
     
       13. The near-eye optical system of  claim 10 , wherein a planar area is provided between the plurality of fourth reflective inclined surfaces. 
     
     
       14. The near-eye optical system of  claim 10 , wherein the third reflective inclined surface is a surface of a convex structure at one end of the fourth surface. 
     
     
       15. The near-eye optical system of  claim 1 , wherein a viewing angle range formed by the first portion of the image beam at a projection target and a viewing angle range formed by the second portion of the image beam at the projection target are partially overlapped. 
     
     
       16. The near-eye optical system of  claim 15 , wherein viewing angle ranges of adjacent first reflective inclined surfaces formed at the projection target are partially overlapped with each other, and viewing angle ranges of adjacent second reflective inclined surfaces formed at the projection target are partially overlapped with each other. 
     
     
       17. The near-eye optical system of  claim 16 , wherein the plurality of first reflective inclined surfaces are arranged at non-equidistant intervals, and the plurality of second reflective inclined surfaces are arranged at non-equidistant intervals. 
     
     
       18. The near-eye optical system of  claim 1 , further comprising a projection device configured to emit the image beam toward the first surface and align the image beam with the first beam-splitting surface and the second beam-splitting surface. 
     
     
       19. The near-eye optical system of  claim 1 , wherein the first beam-splitting surface and the second beam-splitting surface are formed by a partially-transmissive and partially-reflective film embedded in the first optical waveguide. 
     
     
       20. The near-eye optical system of  claim 1 , wherein the first beam-splitting surface and the second beam-splitting surface are V-shaped. 
     
     
       21. The near-eye optical system of  claim 1 , wherein the planar area is provided between the plurality of first reflective inclined surfaces. 
     
     
       22. The near-eye optical system of  claim 1 , wherein a planar area is provided between the plurality of second reflective inclined surfaces.